SOLVED!
Thanks for all the help everyone! As usual, this forum (and all of you on it) has proved its worth!
In the end, the problem was indeed that the wiper linkage was
binding up....
All of the joints were a little bit sticky, but nothing problematic. I lubed them up anyway (for the future,) but to no avail for the current problem. Then I noticed that at the very beginning of the wiper cycle, the motor crank arm was making contact with the bracket that holds the motor in place. There are two metal bumps on the bracket, and the crank arm was completely unable to move because of that. It was tough to notice at the beginning, as it only made contact when the bolt holding the crank arm onto the motor was fully torqued down, and in troubleshooting I had removed the assembly from the motor.
The fix!
In typical "outback mechanic" fashion, my final solution was to add 3 washers in between where the motor and motor crank arm connect. This raised the crank arm
just enough to clear the two metal bumps. Should be good to go now! I put a 20A fuse back in (as specified), in place of the 30A, and it's all running smoothly!
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